Platelet factor 4 plasma levels at rest and after exercise in patients with recent myocardial infarction

Physical activity and prostanoids

Physical activity plays an important role in the prevention of ischaemic heart disease. However, data on the mediating mechanisms are only partly established, and concentrated mainly on plasma lipoproteins. Prostanoids, especially prostacyclin and thromboxane, through their effects on vascular endothelium, platelet function, and interaction with lipoproteins, are postulated to be centrally involved in the pathogenesis of atherosclerosis. The reported acute effects of physical activity on prostanoids and platelet function are contradictory and may be considered both beneficial and unfavourable. On the other hand, although even less is reported on the response to regular exercise, data appear more favourable in relation to atherosclerosis. Currently, data on physical activity and prostanoids, including both acute and chronic effects, are limited and necessitate additional, systematic studies on dose-response relationships.

A systematic review of the effects of acute psychological stress and physical activity on haemorheology, coagulation, fibrinolysis and platelet reactivity: Implications for the pathogenesis of acute coronary syndromes

Physical activity and psychological stress are two potential triggers for the onset of acute coronary syndromes (ACS). To examine the mechanisms underlying this association, we systematically reviewed the literature to determine the effects of acute psychological stress and physical activity on haemorheology and haemostasis. Studies examining the haemorheological and haemostatic response to an acute bout of physical activity (i.e. <60 min) or laboratory psychological stress task were eligible for inclusion. The experimental evidence, although compromised by various methodological weaknesses, suggests that low and moderate intensity physical activity may be cardio-protective through beneficial effects on fibrinolytic system. High levels of physical activity, and psychological to a lesser extent, have been consistently associated with robust changes in haemorheology and haemostasis. Such findings imply that such activities may have the potential to trigger the onset of ACS, although in reality this may be limited sedentary individual and/or those with pre-existing vascular disease. In addition, the data also suggest that individuals may be at a greatest risk of stress-induced thrombogenesis in the period immediately following physical activity or psychological stress, rather than during the activity per se. In conclusion, psychological stress and physical activity may act as potential triggers for the onset of ACS via effects on haemostasis and haemorheology.